Method for preparing nitrile compound through oxidative cracking of sulfur-containing compound

Abstract

The invention provides a method for preparing nitrile compounds by oxidizing and breaking carbon-sulfur bonds (C-S) of sulfur-containing compounds. The method comprises the following steps: adding a sulfur-containing compound, a nitrogen source and a nitrogen-doped mesoporous carbon supported cobalt-based catalyst into a solvent, putting the mixture into a pressure container, sealing, introducing 1.0 MPa oxygen source gas, and reacting at 150-170 DEG C for 6-48 hours, so as to oxidize and break a carbon-sulfur bond into a corresponding nitrile compound. The reaction system disclosed by the invention has the advantages of good functional group compatibility and substrate universality, high catalyst activity, recyclability, easiness in control of reaction conditions, simple post-treatment, accordance with green and sustainable chemical concepts and the like, and has a very good application prospect.

Description

Technical Field

[0001] The invention relates to the field of chemistry and chemical engineering, and in particular to a method for preparing nitrile compounds by oxidative cracking of sulfur-containing compounds. Background Art

[0002] Aromatic nitriles have a wide range of applications in modern organic synthesis, as they frequently occur as useful structural motifs in many natural products, drugs, herbicides, and dyes. In addition, they can serve as versatile intermediates for many synthetic targets, including amines, amides, carboxylic acids, and nitrogen-containing heterocycles. Therefore, the preparation of aromatic nitriles has attracted much attention. To date, aromatic nitriles have been synthesized from a variety of substrates, such as aromatic diazonium salts, aromatic halides, aromatic hydrocarbons, amines, amides, azides, oximes, aldehydes, ketones, aromatic boronic acids, terminal alkynes, aromatic carboxylic acids, and phenols.

[0003] However, most reported methods have certain disadvantages, including long reaction times, low yields, the use of highly toxic reagents such as hydrocyanic acid or metal cyanides, the need to use expensive and excessive catalysts, and harsh reaction conditions. Therefore, it is very important to develop milder and greener methods for the synthesis of aromatic nitriles.

[0004] At present, the only products reported for the selective cleavage of carbon-sulfur bonds are aldehydes, ketones, etc., and the method for preparing nitrile compounds by oxidative cleavage of carbon-sulfur bonds (CS) of sulfur-containing compounds has not been reported. This method not only provides a new way to prepare organic nitriles, but also provides a new way to convert and utilize sulfur-containing compounds. Summary of the invention

[0005] The present invention provides a method for preparing nitrile compounds efficiently and at low cost by achieving oxidative cleavage of carbon-sulfur bonds of sulfur-containing compounds. The method uses the sulfur-containing compound as a substrate and oxygen as an oxygen source. Under the action of a catalyst, the sulfur-containing compound undergoes oxidative cleavage to generate nitrile compounds. The method has substrate universality, the catalyst can be recycled, oxygen is used as an oxygen source, and the method is economical, environmentally friendly, and in line with the concept of green and sustainable development.

[0006] The technical solution adopted by the present invention is:

[0007] A method for preparing nitrile compounds by oxidatively breaking carbon-sulfur bonds of sulfur-containing compounds: adding the sulfur-containing compound, a nitrogen-doped mesoporous carbon-supported cobalt-based catalyst, a nitrogen source and a solvent into a 5 mL reaction bottle, and sealing it with a polytetrafluoroethylene stopper with a hole; transferring it to a stainless steel high-pressure reactor, filling it with 1.0 MPa oxygen source gas, evacuating it, and repeating it three times; placing the reactor in a 150-170° C. oil bath pot for reaction for 6-48 hours, so that the carbon-sulfur bonds can be oxidatively broken to form corresponding nitrile compounds.

[0008] 1. In the above technical scheme, the preparation process of the nitrogen-doped mesoporous carbon-supported cobalt-based catalyst is as follows: weigh 3-6g of silica sol (preferably 4-5g), add it to 30-60mL of water (H2O) (preferably 40-50mL), stir at room temperature until mixed uniformly, and obtain a mixed solution A; weigh 0.2-1.0g of 1,10-phenanthroline (preferably 0.4-0.6g) and 0.1-0.5g of cobalt acetate (preferably 0.2-0.3g), add them to 5-15mL of water (preferably 10-12mL), stir at room temperature, and obtain a mixed solution B; slowly add solution B dropwise to the mixed solution A, and stir the mixture at 50-70°C for more than 3 hours; then evaporate to dryness at 100-120°C to obtain a dry solid, grind it; then roast it at 800-900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 800-900°C is 3-10°C min -1 ), calcined and cooled to room temperature to obtain a black powder, soaked in 15-30% HF for more than 24 hours, finally washed with deionized water until neutral, and dried in an oven at 80-120°C to obtain the target catalyst Co-NC; wherein the mass content of Co is 0.1-2wt%, and the mass content of N is 1-5wt%.

[0009] 2. In the above technical solution, in the sulfur-containing compound molecule, the benzene ring has one or more of phenyl, naphthyl, thiophene ring, and pyridine ring with other substituents;

[0010] The other substituents on the benzene ring are one or more of -CH3, -OCH3, -C(CH3)3, -F, -Cl, -Br, -CF3;

[0011] In sulfur-containing compounds having other substituents on the benzene ring, the positions of the other substituents are ortho, meta or para;

[0012] In the sulfur-containing compound having other substituents on the benzene ring, the number of other substituents is 1, 2, 3, 4 or 5;

[0013] 3. In the above technical scheme, the nitrogen source is an alkaline inorganic compound, including one or more of ammonium sulfate, ammonium carbonate, ammonium chloride, ammonium bicarbonate, ammonium oxalate, ammonium acetate, and ammonia water; the molar ratio of the added amount of the nitrogen source to the sulfur-containing reaction substrate is 1-6, preferably 4-5.

[0014] 4. In the above technical scheme, the solvent is one or more of 1,4-dioxane, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), toluene, tert-amyl alcohol, acetonitrile, n-heptane, and methanol, and its amount is 1-4 mL, preferably 2-3 mL, for every 0.25 mmol of alkyne compound.

[0015] 5. In the above technical solution, the reaction temperature is 100-180°C, preferably 150-170°C; the reaction time is 4-50h, preferably 6-48h.

[0016] 6. In the above technical solution, the molar ratio of the amount of catalyst added to the amount of sulfur-containing reactants fed is 0.01-0.15, preferably 0.05-0.1, based on the molar number of Co.

[0017] 7. In the above technical solution, the oxygen source gas used is one or both of pure oxygen and air; the pressure of the oxygen source gas used is 0.2-2.0 MPa, preferably 1.0-1.5 MPa.

[0018] The system described in the present invention can efficiently prepare nitrile compounds, has low cost, a wide substrate range, high catalyst activity and can be recycled, and the oxygen used is cheap, green and abundant, has no pollution to the environment, and is of great significance to the catalytic oxidation method for developing a green economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the nitrogen-doped mesoporous carbon-supported cobalt-based catalyst prepared as described below.

[0020] Figure 2 This is a transmission electron microscope (TEM) image of the nitrogen-doped mesoporous carbon-supported cobalt-based catalyst prepared as described below. DETAILED DESCRIPTION

[0021] The following examples will help to understand the present invention, but the present invention is not limited thereto.

[0022] The preparation method of the nitrogen-doped mesoporous carbon-supported cobalt-based catalyst used in the following example is as follows: 4g of silica sol is weighed, added to 50mL of water (H2O), stirred at room temperature until mixed, and mixed solution A is obtained; 0.5g of 1,10-phenanthroline and 0.2g of cobalt acetate are weighed, added to 10mL of water, stirred at room temperature, and mixed solution B is obtained; solution B is slowly added dropwise to mixed solution A, and the mixture is stirred at 60°C for more than 3 hours; then evaporated to dryness at 100°C to obtain a dry solid, which is ground; then calcined at 900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 900°C is 5°C min-1), and the black powder obtained after calcination is cooled to room temperature, soaked with HF with a mass concentration of 20% for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C to obtain the target catalyst Co-NC. The mass content of Co is 0.8wt%, the mass content of N is 3.1wt%, and the pore size range is 2-50nm.

[0023] The preparation method of the nitrogen-doped mesoporous carbon-supported cobalt-based catalyst (not acid-washed) used in the following example is as follows: weigh 4g of silica sol, add it to 50mL of water (H2O), stir at room temperature until mixed, and obtain a mixed solution A; weigh 0.5g of 1,10-phenanthroline and 0.2g of cobalt acetate, add them to 10mL of water, stir at room temperature, and obtain a mixed solution B; slowly drop the B solution into the mixed solution A, and stir the mixture at 60°C for more than 3 hours; then evaporate to dryness at 100°C to obtain a dry solid, grind it; then roast it at 900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 900°C is 5°C min-1), and cool it to room temperature after calcination to obtain a black powder, that is, the target catalyst Co-NC (not acid-washed). The mass content of Co is 1.5wt%, the mass content of N is 3.5wt%, and the pore size range is 2-50nm.

[0024] The preparation method of the nitrogen-doped mesoporous carbon-supported zinc-based catalyst used in the following example is as follows: 4g of silica sol is weighed, added to 50mL of water (H2O), stirred at room temperature until mixed, and mixed solution A is obtained; 0.5g of 1,10-phenanthroline and 0.3g of zinc acetate are weighed, added to 10mL of water, stirred at room temperature, and mixed solution B is obtained; solution B is slowly added dropwise to mixed solution A, and the mixture is stirred at 60°C for more than 3 hours; then evaporated to dryness at 100°C to obtain a dry solid, which is ground; then calcined at 900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 900°C is 5°C min-1), and the black powder obtained after calcination is cooled to room temperature, soaked with HF with a mass concentration of 20% for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C to obtain the target catalyst Zn-NC. The mass content of Zn is 0.6wt%, the mass content of N is 3.0wt%, and the pore size range is 2-50nm.

[0025] The preparation method of the nitrogen-doped mesoporous carbon-supported iron-based catalyst used in the following example is as follows: 4g of silica sol is weighed, added to 50mL of water (H2O), stirred at room temperature until mixed, and mixed solution A is obtained; 0.5g of 1,10-phenanthroline and 0.2g of ferric acetate are weighed, added to 10mL of water, stirred at room temperature, and mixed solution B is obtained; solution B is slowly added dropwise to mixed solution A, and the mixture is stirred at 60°C for more than 3 hours; then evaporated to dryness at 100°C to obtain a dry solid, which is ground; then calcined at 900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 900°C is 5°C min-1), and the black powder obtained after calcination is cooled to room temperature, soaked with HF with a mass concentration of 20% for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C to obtain the target catalyst Fe-NC. The Fe mass content is 0.9wt%, the N mass content is 3.7wt%, and the pore size range is 2-50nm.

[0026] The preparation method of the copper-based catalyst supported by nitrogen-doped mesoporous carbon used in the following example is as follows: 4g of silica sol is weighed, added to 50mL of water (H2O), stirred at room temperature until mixed, and mixed solution A is obtained; 0.5g of 1,10-phenanthroline and 0.2g of copper acetate are weighed, added to 10mL of water, stirred at room temperature, and mixed solution B is obtained; solution B is slowly added dropwise to mixed solution A, and the mixture is stirred at 60°C for more than 3 hours; then evaporated to dryness at 100°C to obtain a dry solid, which is ground; then calcined at 900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 900°C is 5°C min-1), and the black powder obtained after calcination is cooled to room temperature, soaked in HF with a mass concentration of 20% for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C to obtain the target catalyst Cu-NC. The mass content of Cu is 1.1wt%, the mass content of N is 3.2wt%, and the pore size range is 2-50nm.

[0027] The preparation method of the nitrogen-doped mesoporous carbon-supported non-metallic catalyst used in the following example is as follows: 4 g of silica sol is weighed, added to 50 mL of water (H2O), and stirred at room temperature until mixed to obtain a mixed solution A; 0.5 g of 1,10-phenanthroline is weighed, added to water, and stirred at room temperature to obtain a mixed solution B; the B solution is slowly added dropwise to the mixed solution A, and the mixture is stirred at 60°C for more than 3 hours, and then evaporated to dryness at 100°C to obtain a dry solid, which is ground; and then calcined at 900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 900°C is 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was soaked in HF with a mass concentration of 20% for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C to obtain the target catalyst NC, wherein the mass content of N is 4.5wt% and the pore size range is 2-50nm.

[0028] Example 1

[0029] Benzyl mercaptan (0.25 mmol), Co-NC (relative to the raw material 5 mol%, in terms of the molar number of Co), NH3·H2O (1.0 mmol) and 2 mL of tert-amyl alcohol were added to a 5 mL reaction tube in sequence, sealed with a polytetrafluoroethylene plug with a through hole (aperture of 2 mm), and then transferred to a stainless steel autoclave. The autoclave was filled with 1.0 MPa of oxygen, emptied, and reciprocated oxygenation and emptied 3 times, and finally filled with oxygen pressure to 1.0 MPa. The reactor was placed in a 150° C. oil bath and stirred at 550 rpm for 6 h. After the reaction was completed, the reactor was cooled to room temperature, opened, and 20 mg of internal standard naphthalene and 1 mL of tert-amyl alcohol were added. After stirring evenly, the mixture was ultrasonicated and centrifuged. An appropriate amount of the clear liquid was taken and the qualitative product was detected by gas chromatography-mass spectrometry. The quantitative conversion rate of the substrate benzyl mercaptan and the yield of the product benzonitrile by gas chromatography internal standard method are shown in Table 1.

[0030] Example 2-33

[0031] Except for the catalyst and dosage, pressure and reaction time, the catalyst activity evaluation is the same as that in Example 1. The reaction conditions and catalytic reaction results are shown in Table 1. It can be seen from Table 1 that the catalyst and dosage, oxygen pressure, nitrogen source type, reaction temperature and reaction time have an effect on the catalytic effect. With the increase of reaction temperature (Examples 1 and 2, 3), oxygen source type, pressure (Examples 1 and 4-6) and reaction time (Examples 1 and 7, 8), the yield increases, and the amount and type of nitrogen source (Examples 1 and 9-18), solvent type (Examples 1 and 19-25), the amount and type of catalyst (Examples 1 and 26-33), the catalytic effect is also different.

[0032] Table 1 Preparation of organic nitrile by oxidative cleavage of benzyl mercaptan

[0033]

[0034]

[0035] The amount of catalyst refers to the mol% of the raw material based on the metal; NC means that it has the same mass as metal-NC;

[0036] Embodiment 34-84

[0037] Except for the different substrates, the catalyst activity evaluation was the same as in Example 1, the catalyst dosage was 0.04-0.08 g, and the reaction time was 6-48 h. The substrates and catalytic reaction results are shown in Table 2. All sulfur-containing substrates can undergo oxidative cleavage to generate corresponding organic nitrile compounds, which shows the universality of this method.

[0038] Table 2 Oxidative cleavage of sulfur-containing substrates

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045] The invention has a wide substrate range, high oxidation efficiency, good selectivity and high yield; it uses oxygen as an oxygen source, is economical and environmentally friendly, conforms to the concept of green and sustainable development, and has good application prospects.

Claims

1. A method for preparing nitrile compounds by oxidative cracking of sulfur-containing compounds, characterized in that: A sulfur-containing compound, a nitrogen source and a nitrogen-doped mesoporous carbon-supported cobalt-based catalyst are added to a solvent, placed in a high-pressure reactor, and an oxygen source gas of 0.2-2.0 MPa is introduced. The reaction is carried out at 100-180° C. for 6-48 hours to oxidatively break the carbon-sulfur bond (CS) into the corresponding nitrile compound.

2. The method according to claim 1: The preparation process of the nitrogen-doped mesoporous carbon-supported cobalt-based catalyst is as follows: weigh 3-6g of silica sol (preferably 4-5g), add it to 30-60mL of water (H2O) (preferably 40-50mL), stir at room temperature until mixed uniformly, and obtain a mixed solution A; weigh 0.2-1.0g of 1,10-phenanthroline (preferably 0.4-0.6g) and 0.1-0.5g of cobalt acetate (preferably 0.2-0.3g), add them to 5-15mL of water (preferably 10-12mL), stir at room temperature, and obtain a mixed solution B; slowly dropwise add the B solution to the mixed solution A, and stir the mixture at 50-70°C for more than 3 hours; then evaporate to dryness at 100-120°C to obtain a dry solid, grind it; then roast it at 800-900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 800-900°C is 3-10°C min -1 ), calcined and cooled to room temperature to obtain a black powder, soaked in 15-30% HF for more than 24 hours, finally washed with deionized water until neutral, and dried in an oven at 80-120°C to obtain the target catalyst Co-NC; wherein the mass content of Co is 0.1-2wt%, and the mass content of N is 1-5wt%.

3. The method for preparing nitrile compounds by oxidative cracking of sulfur-containing compounds according to claim 1, characterized in that: The nitrogen source is an alkaline inorganic compound, including one or more of ammonium sulfate, ammonium carbonate, ammonium chloride, ammonium bicarbonate, ammonium oxalate, ammonium acetate, and ammonia water; the molar ratio of the nitrogen source added to the sulfur-containing compound reaction substrate is 1-6, preferably 4-5.

4. The method for preparing nitrile compounds by oxidative cracking of sulfur-containing compounds according to claim 1, characterized in that: The solvent is one or more of 1,4-dioxane, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), toluene, tert-amyl alcohol, acetonitrile, n-heptane, and methanol, and the amount thereof is 1-4 mL, preferably 2-3 mL, for every 0.25 mmol of the alkyne compound.

5. The method according to claim 1, characterized in that The reaction temperature is 100-180° C., preferably 150-170° C.; the reaction time is 4-50 h, preferably 6-48 h.

6. The method according to claim 1, characterized in that The molar ratio of the amount of the catalyst added to the amount of the sulfur compound reactant added is 0.01-0.15, preferably 0.05-0.1, based on the molar number of Co.

7. The method according to claim 1, characterized in that The oxygen source gas used is one or both of pure oxygen and air; the pressure of the oxygen source gas used is 0.2-2.0 MPa, preferably 1.0 MPa.

8. The method according to claim 1, characterized in that: The sulfur-containing compound is a benzyl mercaptan (ether) compound (Benzyl mercaptan: R2 = H; benzyl sulfide: R2 = C1-C20 alkyl), in the benzyl mercaptan (ether) compound molecule, the substituent R1 on the benzene ring is one or more of phenyl, naphthyl, thiophene ring, pyridine ring, -CH3, -OCH3, -C(CH3)3, -F, -Cl, -Br, -CF3; or, the benzene ring can be replaced by a naphthalene ring, a thiophene ring or a pyridine ring; In the benzyl mercaptan (ether) compound having other substituents on the benzene ring, the position of the other substituent R1 is ortho, meta or para; In the benzyl mercaptan (ether) compound having other substituents on the benzyl ring, the number of the other substituents is 1, 2, 3, 4 or 5.

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